Light-sensitive silver halide color photographic emulsions

ABSTRACT

lor-photographic emulsion which comprises, as protected cyan coupler, a compound of the structural formula

United States Patent Inventors Keljl Kasai;

Yoelnobu Nakagawa, both of Tokyo, Japan Appl. No. 862,643

Filed Sept. 24, 1969 Patented Nov. 23, 1971 Assignee Konlshlroku Photo Industry Co., Ltd.

Tokyo, Japan Priority Sept. 25, 1968 Japan 43/68766 LIGHT-SENSITIVE SILVER HALIDE COLOR Primary Examiner.lohn T. Goolkasian Assistant Examiner-Robert A. Dawson Attorney-Waters, Roditi, Schwartz & Nissen ABSTRACT: improved light-sensitive silver halide colorphotographic emulsions contain a protected cyan coupler having improved solubility in coupler solvents and represented by the formula LIGHT-SENSITIVE SILVER HALIDE COLOR PHOTOGRAPHIC EMULSIONS ONH(CHz)uC 'a wherein X is hydrogen or chlorine atom and n is an integer of 7 to 18. This compound is still unsatisfactory because of its solubility in a solvent for couplers, although it is rather well soluble in comparison with other known couplers. Therefore, the main purpose of the invention is to obtain highly increased solubility of the coupler compound with the result that the solvent amount required can be minimized.

Under the above situation, we have found that a new compound of the formula which can be synthesized with technical ease and at an economical cost is useful as protected cyan coupler for a lightsensitive silver halide color-photographic emulsion, without any harmful influence on the photographic properties of said emulsion.

Good solubility of the coupler compound of the invention in a solvent for couplers will be clear by reference to the following table.

A B C Coupler of the invention 23C 0.5 ml. No precipitation Coupler of the Precipitation formula (l) 50 C. l.5 ml. occurs after wherein n=ltt six hours Coupler of the Precipitation formula III 45 C. L2 ml. occurs after \herem n=l-l two hours Coupler of the Precipitation tl) 52 C. 2.0 ml. occurs wherein n=K immediately In the above table; A means a temperature at which complete dissolution is obtained when 0.5 g. of the coupler is added to a mixture consisting of 0.25 ml. of tricresyl phosphate and 0.25 ml. of butyl acetate and the resulting mixture is warmed with stirring. The symbol B means the amount of the solvent l:l tricresyl phosphate and butyl acetate) sufficient to obtain complete dissolution of 0.5 g. of the coupler on a water bath at 30 C. The symbol C" means the tendency of crystal separation when the solution obtained under the condition A is allowed to stand at 23 C.

As apparent from the above table, the coupler compound of the invention is excellent not only in solubility in a solvent but also in stability of its dispersion. When it is incorporated into a light-sensitive silver halide color-photographic emulsion. it does not cause any harmful effect on the photographic properties of the emulsion.

The following is one example to show the synthetic procedures for a coupler of the present invention.

89.0 g. (0.4 mol) of 4-chloro-l-hydroxynaphthoic acid, together with 45.1 g. of phenol and 73.6 g. of phosphorus oxychloride, are gradually heated on an oil bath to a temperature of l l5-l20 C. over about 20 minutes. Stirring is continued for two hours. The resulting reaction mixture is poured into 2.5 l. of warm water kept at C. Stirring is continued for another 30 minutes at the same temperature. Then, the reaction mixture is cooled with ice to an internal temperature of l5-2O C. and then filtered. The remaining filter cake is washed with water three times. This is pulverized and further washed with water and then twice with methanol. After drying, the pale yellow crystalline mass is recrystallized from methyl cellusolve. 74.5 g. of l-hydroxy-4-chloro-2-naphthoic acid phenyl ester is obtained.

29.8 g. of this compound is heated with 26.7 g. of octadecenyl amine (oleyl amine) on an oil bath. Heating is carried out for 10 minutes at a bath temperature of -l00 C. The resulting mixture is subjected to distillation under reduced pressure thereby to remove the produced phenol completely. The reaction is complete within about 60 minutes and this is indicated by cessation of the phenol formation. The remaining brown-colored syrup is allowed to cool and treated with 300 ml. of n-hexane. The separated yellow crystalline mass is collected by filtration, washed with n-hexane twice and then dried under reduced pressure. The white amorphous crystals obtained are recrystallized from methanol. 31.0 g. (66 percent of the theoretical yield) of l-hydroxy-4-chloro-2-octadecenyl naphthoamide is obtained as white crystalline scales. m.p. 80-83 C. The result of elementary analysis for C H NO CI is as follows:

The coupler of the invention can be produced easily and at high purity on the commercial scale. Further it can form an excellent color image because of its good dispersability in a photographic emulsion with maintaining the photographic properties of the emulsion unchanged.

The preparation of a light-sensitive silver halide colorphotographic emulsion using said coupler compound the protected coupler can be made in the same manner as conventionally known in the art. For example, the compound is dissolved in a high boiling solvent, such as dibutyl phthalate, tricresyl phosphate, etc., singly or in combination with a low boiling solvent, such as butyl acetate, butyl propionate, etc., and the resulting solution is mixed with a gelatinous aqueous solution containing a surface active agent. The resulting mixture is emulsified by means of a high speed rotary mixer or a colloid mill and the resulting emulsion is directly added to a silver halide photographic emulsion which is then coated on a film base or baryta paper or the like support. The coated support is dried to remove the majority of the low boiling solvent if it is used. Alternatively, the above-mentioned coupler emulsion is cooled, set, cut to nudles and then washed with water to remove the low boiling solvent. This coupler emulsion is added to the photographic emulsion which in turn is coated on the support and dried. Thus, a light-sensitive silver halide color-photographic material is obtained. The amount of the coupler compound to be added to the light-sensitive colorphotographic emulsion preferably is within the range of l5-l00 g. per mole of the silver halide. However, this is not critical.

The thus obtained light-sensitive color photographic material is exposed to light and then treated with a paraphen- EXAMPLE g. of the coupler compound as indicated before is dissolved completely at 25 C. in ml. of a l:l mixture of tricresyl phosphate and butyl acetate. The resulting solution is added with 5 ml. of an aqueous solution of 10 percent Alkanol B and 200 ml. of an aqueous solution of 5 percent gelatine and the resulting mixture is subjected to a colloid mill.

The resulting dispersion is added to 500 g. of a gelatinous silver iodobromide emulsion, which is then coated on a film base and dried to produce a light-sensitive silver halide colorphotographic film.

The thus obtained film after exposure to light, is treated for 10 minutes with a developing solution of the formulation:

Metol 3.0 g. Anhydrous sodium sulfilc 60.0 g. Hydroquinone 6.0 g. Anhydrous sodium carbonate 50.0 g.

Potassium bromide Water to make L000 ml.

Then, the developed material is treated by stopping, fixing, water-washing and bleaching in the manner known in the art and then washed with running water for minutes, followed by drying. A highly transparent, cyan color image having an absorption maximum at 690 mucan be obtained.

A part of this sample bearing the cyan color image is kept for 5 days at 50 C. under relative humidity of 80 percent, while another part of the same sample is kept for 4 days at 40 C. in a Fade-O-Meter. In both cases, fading is determined, which is expressed in terms of the remaining percentage as compared with the original image density rated as lOO. The results are set forth in the following table.

In the above, the control samples (I), (2) and (3) are prepared by using one of the known couplers of the formula respectively, instead of the coupler compound of the present invention in the color photographic emulsion.

As apparent from the above, the sample according to the invention is clearly superior in color image stability against heat, humidity and light to the control samples. Further, the cyan color image obtained from the coupler of the invention is quite safe from the decrease of image density due to the variation of pH of a treating bath and time of water washing following bleaching.

What we claim is:

l. A light-sensitive silver halide color-photographic emulsion which comprises, as protected cyan coupler, a compound of the structural formula 

